
❑Cooling system service. Clean the cooling
system filler cap with clean water, clean
the core, pressure test the cap and the
system for proper pressure capability, and
inspect condition of cooling and heater
hoses and clamps. Replace hoses if cracked,
swollen, or damaged.
❑Replace fuel filter(s) (or every 12 months,
whichever occurs first).(2)
❑Steering system service.(12)
❑Front and rear suspension service.(13)
❑Spring-to-axle U-bolts and shackle bolts
service.(15)
❑Exhaust system service (or every 6 months,
whichever occurs first).(2) (3) (16)
❑Inspect door hinge pins and bushings and
replace as necessary.
❑Wheel bearing (grease type) service (and
whenever hubs are removed).(22) (36)
❑Wheels and tires service.(14)
❑Hydraulic brake service (or every 6 months,
whichever occurs first).(6) (36)
❑Parking brake service (or every 6 months,
whichever occurs first).(21)❑Air brake service (or every 6 months, whichever
occurs first).(32)
❑Air brake automatic slack adjuster service (or
every 500 hours, whichever occurs first).(33)
❑Check air brake relay valve operation and check
for leaks (or every month, or every 300 hours,
whichever occurs first).
❑Clean air brake application valve (or every
3 months, or every 300 hours, whichever
occurs first). Lubricate linkage.
❑Air brake chamber service (or every 2 months,
whichever occurs first).(34)
❑Air brake system valve service (or every
3 months, or every 900 hours, whichever
occurs first).(37)
❑C600, C700, and C800 Gasoline Engines
Only: Engine drive belts service (or every
12 months, whichever occurs first).(17)
❑Thermostatically controlled engine cooling
fan service.(3) (19)
❑Shields and underhood insulation
service.(3) (4) (20)
❑Rear axle air shift motor service.(10)
380

(22)= Wheel bearing service:
•Grease type — Clean, inspect, and lubricate
with the proper wheel bearing grease at
designated intervals or when hubs are
removed. SeePart C: Recommended Fluids
and Lubricants on page 397.
•Oil-filled type — Some wheel bearings are
lubricated by axle lubricant. When you
have oil-filled hubs, use lubricant identical
to that used in the axle. Lubricant change
intervals are the same for front and rear
axles. However, you must maintain the proper
oil level between change intervals. See
Front Wheel Bearings with Oil-Filled Hubs
on page 319andPart C: Recommended
Fluids and Lubricants on page 397.
(23)= Check the air intake system installation
to see that gaskets are seated properly and
all hose connections, fasteners, and other
components are tight. Tighten connections
and fasteners or replace parts as required.(24)= Evaporative Control System Service,
if equipped: Check all fuel and vapor lines and
hoses for proper connections and correct routing
(or every 24 months, whichever occurs first).
Replace parts as needed.
(25)= Replace spark plugs. Inspect wires for
damage. Check the wire boot and boot heat
shield fit at spark plugs and coil. Replace parts
as needed.
(26)= Check the fuel tank, fuel cap and fuel lines
for damage which could cause leakage. Inspect
fuel cap for correct sealing ability and any
indications of damage. Check fuel cap gasket
for even filler neck imprint. Replace parts as
needed.
(27)= Check Exhaust Gas Recirculation (EGR)
system as described in the service manual.
SeeService Publications Ordering Information
on page 415.
388

Part B: Owner Checks and Services
Listed in this part are owner checks and services
which should be performed at the intervals
specified to help ensure the safety, dependability
and emission control performance of your
vehicle.
For your safety and that of others, any of the
safety-related components that may have been
damaged in an accident should be checked
and any needed repairs made before operating
the vehicle.
At the minimum, these routine checks should be
made every 6 months or 6,000 miles (10 000 km),
whichever occurs first. Whenever repairs are
needed, have them completed before operating
the vehicle.
At Each Fuel Fill
It is important for you or a service station attendant
to perform these underhood checks at each fuel ll.
Engine Oil Level Check
Check the engine oil level and add the proper
oil if necessary. SeeEngine Oil (Caterpillar®
Diesel Engine) on page 268orEngine Oil
(Gasoline Engine) on page 268orEngine Oil
(DURAMAX
®/Isuzu Diesel Engine) on page 272.
Engine Coolant Level Check
Check the engine coolant level and add
DEX-COOL®coolant mixture if necessary. See
Engine Coolant (Gas and DURAMAX®/Isuzu
Engines) on page 284orEngine Coolant
(Caterpillar
®Diesel Engines) on page 287.
Windshield Washer Fluid Level Check
Check the windshield washer fluid level in the
windshield washer fluid reservoir and add
the proper fluid if necessary. SeeWindshield
Washer Fluid on page 296.
Tire In ation Check
Check tire inflation cold. Make sure the tires are
inflated to the correct pressures. SeeLoading Your
Vehicle on page 238andIn ation - Tire Pressure
on page 322.
391

Lamps Check
Check panel lighting, warning lights, indicator
lights, and interior lamps. On the outside,
check: license plate lamps, sidemarker lamps,
reflectors or lights on outside mirrors, headlamps,
parking lamps, identification and clearance
lamps, taillamps, brake lamps, turn signals,
backup lamps, and hazard warning flashers.
Have headlamp aim checked at once if beams
seem improperly aimed.
Glass, Mirrors, Lamps and/or
Re ectors Condition Check
Look for broken, scratched, dirty, or damaged
glass, mirrors, lamps, or reflectors that could
reduce the view or visibility or cause injury.
Replace, clean or repair promptly.
Door Latches Check
Check that doors close, latch, and lock tightly.
Check for broken, damaged, or missing parts that
might prevent tight latching.
Hood Latches Check
Check that the hood closes firmly. Check for
broken, damaged, loose, or missing parts
that might prevent tight latching. Make sure the
secondary latch (if equipped) keeps the hood
from opening all the way when the primary latch
is released.
Fluid Leaks Check
Check for fuel, coolant, oil, or other fluid leaks by
looking at the surface beneath the vehicle after
it has been parked for awhile.
395

Underbody Inspection
Corrosive materials used for ice, snow removal,
and dust control can collect on the underbody.
If these materials are not removed, accelerated
corrosion (rust) can occur on underbody parts
such as fuel lines, frame, floor pan, and exhaust
system. At least every spring, flush these materials
from the underbody with plain water. Take care
to clean well any areas where mud and other
debris can collect. Sediment packed in closed
areas of the frame should be loosened before
being flushed.
Engine Cover Check
Check that the cab’s engine cover and seal
(if equipped) are not torn or damaged.
Be sure that the cover is clamped down firmly
to the floor.
At Least Once a Year
Key Lock Cylinders Service
Lubricate the key lock cylinders with the lubricant
specified in Part C.
Underbody Flushing Service
At least every spring, use plain water to flush
any corrosive materials from the underbody.
Take care to clean thoroughly any areas where
mud and other debris can collect.
Tractor Protection (Breakaway)
Valve Check
On air brake models, remove, disassemble,
clean, and inspect the tractor protection
(breakaway) valve.
396

Vehicle Data Collection and
Event Data Recorders
Your vehicle, like other modern motor vehicles, has
a number of sophisticated computer systems that
monitor and control several aspects of the vehicle’s
performance. Your vehicle uses on-board vehicle
computers to monitor emission control components
to optimize fuel economy, to monitor conditions for
airbag deployment and, if so equipped, to provide
anti-lock braking and to help the driver control
the vehicle in difficult driving situations. Some
information may be stored during regular operations
to facilitate repair of detected malfunctions; other
information is stored only in a crash event by
computer systems, such as those commonly
called event data recorders (EDR).
In a crash event, computer systems, such as the
Airbag Sensing and Diagnostic Module (SDM)
in your vehicle may record information about the
condition of the vehicle and how it was operated,
such as data related to engine speed, brake
application, throttle position, vehicle speed,safety belt usage, airbag readiness, airbag
performance, and the severity of a collision.
This information has been used to improve vehicle
crash performance and may be used to improve
crash performance of future vehicles and
driving safety. Unlike the data recorders on many
airplanes, these on-board systems do not
record sounds, such as conversation of vehicle
occupants.
To read this information, special equipment is
needed and access to the vehicle or the device
that stores the data is required. GM will not access
information about a crash event or share it with
others other than:
•with the consent of the vehicle owner or,
if the vehicle is leased, with the consent of
the lessee,
•in response to an official request of police or
similar government office,
•as part of GM’s defense of litigation through
the discovery process, or
•as required by law.
409

A
Accessory Power Outlet(s).......................... 156
Adding a Snow Plow or Similar
Equipment................................................ 240
Adding Equipment to Your Airbag-Equipped
Vehicle....................................................... 81
Additives, Fuel............................................ 252
Add-On Electrical Equipment....................... 340
Air Cleaner/Filter, Engine............................. 280
Air Conditioning........................................... 157
Air Conditioning System.............................. 320
Air Pressure Gage...................................... 183
Air Shift Control........................................... 114
Air Suspension............................................ 129
Air Suspension Seats.................................... 13
Airbag
Off Light.................................................. 166
Readiness Light....................................... 165
Airbag Sensing and Diagnostic
Module (SDM).......................................... 409
Airbag System............................................... 68
Adding Equipment to Your
Airbag-Equipped Vehicle......................... 81
Airbag Off Switch....................................... 76
How Does an Airbag Restrain?.................. 73
Servicing Your Airbag-Equipped Vehicle..... 80Airbag System (cont.)
What Makes an Airbag Inflate?.................. 73
What Will You See After an Airbag
Inflates?................................................. 74
When Should an Airbag Inflate?................. 72
Where Are the Airbags?............................. 70
AM-FM Radio.............................................. 186
Antenna, Fixed Mast................................... 204
Anti-Lock Brake System (ABS).................... 212
Anti-Lock Brake, System Warning Light....... 172
Anti-Lock Brakes, Trailer System
Warning Light........................................... 172
Appearance Care
Aluminum or Chrome-Plated Wheels........ 337
Care of Safety Belts................................ 334
Chemical Paint Spotting........................... 338
Cleaning Exterior Lamps/Lenses.............. 335
Cleaning the Inside of Your Vehicle.......... 331
Fabric/Carpet........................................... 333
Finish Care.............................................. 335
Finish Damage......................................... 338
Instrument Panel, Vinyl, and Other
Plastic Surfaces.................................... 334
Sheet Metal Damage............................... 337
Tires........................................................ 337
Underbody Maintenance........................... 338
Vehicle Care/Appearance Materials.......... 339
417

Customer Assistance Information
Customer Assistance for Text Telephone
(TTY) Users.......................................... 406
Customer Assistance Offices.................... 406
Customer Satisfaction Procedure.............. 404
GM Mobility Reimbursement Program...... 407
Reporting Safety Defects to
General Motors..................................... 415
Reporting Safety Defects to the
Canadian Government.......................... 414
Reporting Safety Defects to the
United States Government.................... 414
Roadside Assistance Program.................. 408
Service Publications Ordering
Information........................................... 415
D
Daytime Running Lamps............................. 151
Daytime Running Lamps Indicator Light....... 179
Defensive Driving........................................ 206
Diesel Engine
Engine Alarm and Automatic Shutdown.... 104
Exhaust Brake......................................... 112
Exhaust Restrictor.................................... 108Diesel Engine (cont.)
Fuel......................................................... 253
High Idle System..................................... 106
Starting.................................................... 100
Differential Lock Control, Rear Axle............. 215
Differential Lock Indicator Light.................... 178
Doing Your Own Service Work.................... 249
Dome Lamps............................................... 153
Door
Locks......................................................... 91
Power Door Locks..................................... 92
Driver
Position, Safety Belt................................... 26
Driving
At Night................................................... 223
City.......................................................... 227
Defensive................................................. 206
Drunken................................................... 207
Freeway................................................... 228
Hill and Mountain Roads.......................... 230
In Rain and on Wet Roads...................... 224
Rocking Your Vehicle to Get it Out.......... 236
Tow Hooks............................................... 237
Winter...................................................... 231
Dual Tire Operation..................................... 323
420